The technical scope of the present invention is that of primer tubes, in particular for artillery ammunition.
Primer tubes are intended to ensure the ignition of the propellant charge of a piece of ammunition.
Known primer tubes are generally formed of a rear ignition unit intended to prime a priming composition arranged inside a tubular body integral with the rear unit.
Primer tubes are generally made integral with the ammunition by screwing the rear unit to the ammunition stub base.
Today, the ammunition being used is more and more frequently formed of a combustible case and a generally metallic obstructing base.
Thus, after the ammunition has been fired, the only non-combustible part that is ejected from the weapon, and then temporarily stored inside the turret, is the obstructing base that takes up relatively little space.
Known primer tubes that are formed by a metallic tubular body present the main disadvantage of protruding from the obstructing base. This complicates the ejection of the base from the weapon chamber and its subsequent storage in the turret after firing. Such a primer tube is described in patent FR2343987.
To overcome this disadvantage, patent FR2593905 proposes replacing the metallic tubular body by a heat-shrinkable sheath that ensures the priming tablets are held in place and are integral with the rear unit.
The advantage of such a solution lies in that it ensures the full combustion of the combustible tubular body. The only incombustible part is the rear unit, which is of a height lower than that of the obstructing base. Thus, the ejection and storage of the base are not disturbed.
However, this primer tube has other disadvantages. In fact, the heat-shrinkable sheath acting as the tubular body has a certain flexibility that generates an embattlement, which may lead to its fracture due to vibrations and other mechanical stresses to which the ammunition is subjected during the different transportation and loading phases.
Patent EP0100840 describes a primer tube that incorporates a combustible tubular body that separates from the metallic rear unit. Thus, if the tubular body is not fully consumed, it does not remain attached to the rear unit but is ejected from the barrel. To do this, a separation charge is installed in a cavity made in the rear unit in contact with the tubular body. The main disadvantage of such a solution lies in its complexity, which leads to difficulties in its manufacture and implementation, thereby raising the cost.
The aim of the present invention is to propose a primer tube that overcomes such disadvantages.
Thus, the primer tube according to the invention does not remain attached to the obstructing base after firing and said base can be ejected and stored optimally.
The primer tube according to the invention is of a simple design and reasonable cost.
The invention thus relates to a primer tube, notably for the propellant charge of artillery ammunition, formed of a tubular body accommodating a priming composition, said primer tube characterized in that the tubular body incorporates at least one receiving surface oriented so as to receive the propellant gas pressure generated when the propellant charge is ignited, said gas acting to propel the primer tube.
Advantageously, the pressure receiving surface can be a disk arranged substantially radial to the tubular body.
The disk can be arranged at the upper end of the tubular body.
The disk can incorporate a cylindrical seat of a diameter substantially equal to the internal diameter of a combustible ammunition case.
Advantageously, the disk can incorporate openings allowing the ammunition to be loaded with propellant.
Preferentially, the tubular body can be extended at its lower end by a tubular sleeve.
The tubular sleeve can envelope a rear ignition unit integral with a munition base or an intermediate part integral with the case and a rear ignition unit.
Advantageously, the priming composition will be placed in an internal channel of the tubular body, said channel delimited at its upper end by a wall integral with the disk and at its lower end by a foil.
The priming composition can be pulverulent or formed by a stack of tablets and incorporate an axial channel.
The priming composition can comprise at least two energetic primacords.
The tubular body can has a flared part at its upper end intended to make it easier for the primacords to exit.
A first advantage of the device according to the invention lies in that the tubular body of the primer tube is ejected from the weapon barrel.
A further advantage lies in that after firing the obstructing base of the munition has no protruding elements. It thus takes up little space and can therefore be ejected from the weapon chamber, then optimally stored in the turret.
Another advantage lies in that the combustible case of the munition is stiffened around the disk, thereby improving its mechanical strength.